The methods of analysis failures of squeeze film damper are emphasis on expounded.First, the studies of squeeze film damper of the principal aeroengine manufacture factories in the international have been introduced. It is not only to help the envelopment of squeeze film damper for China but also it raises an inspiration that is to research the failure of squeeze film damper should be based on the collocations of synthetical parameters. Thus the bearing parameter ��B�� and unbalance eccentricity ratio ��U�� are used as the elementary parameters to detail the methods of analysis failures. There are two cases to define the failure . One is the rotor system can not to strit over the critical speed ,and the other is arising the bistable characteristic. The data and character diagram of unable to strid over critical speed ,and three typical bistable curves have been presented.